Hi and thank you for your reply.
Yes I use it however I am not sure this is mandatory as the iOS App doesn't open a connection. It just listen to incoming connection on a dedicated port.
The external hardware does the connections every 10s.
When the issue happens, on the hardware side I have this kind of error:
tcp_input [C172:1] flags=[R.] seq=0, ack=2648339792, win=0 state=SYN_SENT rcv_nxt=0, snd_una=2648339791
nw_endpoint_flow_failed_with_error [C172 192.168.1.75:1234 in_progress channel-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] already failing, returning
And then, if I just open the iOS app, bringing it to foreground for a second and put it back on background, the external hardware will continue to open new connections successfully .... until the next 15 minutes "timeout" .
And the same issue will happen again and again.
So on the iOS App I presume the listener is still active but need the App to bring to foreground regularly and this is not what I expect.
If you think that there is no limitation of having a NWListener on an iOS App that stays active while in background please tell me, so the solution of my issue is elsewhere.
I really don't understand why and don't find any answer.